V3 Fosi mono Kappa 9

[Anglofun]

Afternoon gents!

Your thoughts on 2 48v monoblocks to power the woofer section on Kappa 9's from INFINITY. I have a Classe DR2 for the mid range. And yes, I am on full mode in an ideal world with the V3's.
So basically I would be Bi-amped. Classe for the mid range and highs and the V3's monoblocks for the bass.
Thanks!

 

[everettT]

Afternoon gents!

Your thoughts on 2 48v monoblocks to power the woofer section on Kappa 9's from INFINITY. I have a Classe DR2 for the mid range. And yes, I am on full mode in an ideal world with the V3's.
So basically I would be Bi-amped. Classe for the mid range and highs and the V3's monoblocks for the bass.
Thanks!

Why do you want to passively biamp in the first place? If this is the route you want to go it's best to use identical amps as you could be creating more problems than any possible benefit.

 

[Anglofun]

Why do you want to passively biamp in the first place? If this is the route you want to go it's best to use identical amps as you could be creating more problems than any possible benefit.

Because the midrange quality of the DR2 is quite nice in comparison to the V3.

 

[everettT]

Because the midrange quality of the DR2 is quite nice in comparison to the V3.

I haven't had a chance to listen to both at the same time for comparison purposes but I don't think you're going to gain much, if anything, compared to using one capable amp. Do you feel you're lacking just with the Classe driving the speakers alone and what do you mean by the amp having "midrange quality?"

 

[Anglofun]

I haven't had a chance to listen to both at the same time for comparison purposes but I don't think you're going to gain much, if anything, compared to using one capable amp. Do you feel you're lacking just with the Classe driving the speakers alone and what do you mean by the amp having "midrange quality?"

Not lacking, my main question was is the V3 able to handle the bass section of the Kappa 9? I have them coming in today so I guess I will soon know

 

[everettT]

Not lacking, my main question was is the V3 able to handle the bass section of the Kappa 9? I have them coming in today so I guess I will soon know

They should be able to handle the bass section based on the measurements of the of Fosi. Everything indicates it is competent to below 20hz.

Fosi Audio V3 Mono Amplifier Review

This is a review and detailed measurements of the Fosi Audio V3 Mono class D amplifier. It was sent to me by the company. The price with the power supply I tested is US $139.99. I must say the concept of a "monoblock" amplifier in such a small size runs foul of any expectation a longtime...

www.audiosciencereview.com

 

[Anglofun]

They should be able to handle the bass section based on the measurements of the of Fosi. Everything indicates it is competent to below 20hz.

Fosi Audio V3 Mono Amplifier Review

This is a review and detailed measurements of the Fosi Audio V3 Mono class D amplifier. It was sent to me by the company. The price with the power supply I tested is US $139.99. I must say the concept of a "monoblock" amplifier in such a small size runs foul of any expectation a longtime...

www.audiosciencereview.com

Agreed, fingers crossed cause these speakers are horrid to drive. Tried many but ideally I should have gone with Krell or Mark Levinson. Just didn't want to drop so much on a secondary system.

 

[PENG]

Agreed, fingers crossed cause these speakers are horrid to drive. Tried many but ideally I should have gone with Krell or Mark Levinson. Just didn't want to drop so much on a secondary system.

Your Classe cannot do it on their own but the 2 V3 with 48 v PS will be abe to do a decent job. Sounds like you have a good plan..

 

[everettT]

Agreed, fingers crossed cause these speakers are horrid to drive. Tried many but ideally I should have gone with Krell or Mark Levinson. Just didn't want to drop so much on a secondary system.

Just note that Hypex and Purifi (and all the companies that use their modules) offer state of the art amps at extremely reasonable prices if you ever want to make a change. Good luck with your purchase, it should be fine.

 

[Anglofun]

Just note that Hypex and Purifi (and all the companies that use their modules) offer state of the art amps at extremely reasonable prices if you ever want to make a change. Good luck with your purchase, it should be fine.

I looked at the HYPEX. in monoblocks it quite pricey, like used KRELL or ML pricey. And if I was to put 2k on an amp, just for the warm and fuzzy feel, I would KRELL or ML over HYPEX, can I LOL on this?

 

[PENG]

I looked at the HYPEX. in monoblocks it quite pricey, like used KRELL or ML pricey. And if I was to put 2k on an amp, just for the warm and fuzzy feel, I would KRELL or ML over HYPEX, can I LOL on this?

The Classe is class A right.? That should give you enough warmth (pun intended), when used with 2x V3 mono. My V3, Hypex, Purifi all sounds as good as my much more expensive amps. People pay more for other reasons, often not for better SQ. I think you will be happy with your V3.

 

[PENG]

Agreed, fingers crossed cause these speakers are horrid to drive.

May be that's what people said on the internet but they often said such thing without stated the underlying conditions.

Reality is, such large speaker can be considered power hungry but most of the times there are not if used for less than reference level (like most people do) and seating distance not too far such as less than 4 to 5 meters.

Take a look of the specs, assuming yours are the RS 9 Kappa

If you know how to calculate the power requirements, that's great but if not, just use an online calculator and you will see that with just 20 W, you can get reference level of 105 dB, that's super loud! from 15 feet:

Peak SPL Calculator

So, those who said they were horrid to drive, might be sitting very far in a very large room and/or listen to even above reference level.

Having said that, I don't believe the 102 dB/1w/m is realistic, so I would de-rate it by 13 dB, to say 89 dB and the results would then be:

about 90 dB, from 15 feet, 25 W, or
92 dB, from 12 feet, 25 W, or
105 dB (ref level), 12 feet, with 500 W

You can see that there is truth in the speaker being "horrid to drive" as a general statement, one must know the use case and go from there, and keep in mind I arbitrarily de-rate the sensitivity spec from 102 dB to 89 dB, so in reality, I doubt most would need 500 W from 25 feet to get reference level.

Also, your proposed use case is to use the V3s to drive the 2 12 inch woofers only, so your power requirement would drop below the calculated results shown above.

Such large 4 ohm rated speakers of love "power" or current, but how much you need depends a lot on how loud you want to listen to and your seating distance.

 

[lovinthehd]

Reducing the sensitivity spec from Infinity by 12dB might be a bit much, but haven't seen measurements of those speakers either. That Classe amp is just not very powerful to begin with, might have better results just using the Fosi amps alone. Normally I wouldn't bother with passive bi-amping and would generally agree better to do it with identical amps (or just a more powerful amp to begin with).

 

[MrBoat]

Icepower has a lot of options as well, and those come with an integrated power supply so no additional bricks etc to deal with and are reasonably priced.

 

[Anglofun]

May be that's what people said on the internet but they often said such thing without stated the underlying conditions.

Reality is, such large speaker can be considered power hungry but most of the times there are not if used for less than reference level (like most people do) and seating distance not too far such as less than 4 to 5 meters.

Take a look of the specs, assuming yours are the RS 9 Kappa

View attachment 76520

If you know how to calculate the power requirements, that's great but if not, just use an online calculator and you will see that with just 20 W, you can get reference level of 105 dB, that's super loud! from 15 feet:

Peak SPL Calculator

So, those who said they were horrid to drive, might be sitting very far in a very large room and/or listen to even above reference level.

Having said that, I don't believe the 102 dB/1w/m is realistic, so I would de-rate it by 13 dB, to say 89 dB and the results would then be:

about 90 dB, from 15 feet, 25 W, or
92 dB, from 12 feet, 25 W, or
105 dB (ref level), 12 feet, with 500 W

You can see that there is truth in the speaker being "horrid to drive" as a general statement, one must know the use case and go from there, and keep in mind I arbitrarily de-rate the sensitivity spec from 102 dB to 89 dB, so in reality, I doubt most would need 500 W from 25 feet to get reference level.

Also, your proposed use case is to use the V3s to drive the 2 12 inch woofers only, so your power requirement would drop below the calculated results shown above.

Such large 4 ohm rated speakers of love "power" or current, but how much you need depends a lot on how loud you want to listen to and your seating distance.

Thanks for the input, the problem with the Kappa 9's is at around 40 hz, they drop below 1 ohm causing havoc. I tried Bryston, Plinius, Class D amps and all of them couldn't handle it. Looking at Kappa owners, they all go to monsters (like Krell or Mark Levinson)that can handle the 1 ohm demand.

 

[Anglofun]

Circling back here after installing the V3's with 48v power supplies. Bi amped with the Classe Dr2. Set them up and was unsure about the gain match between my c35 Classe preamp and the V3's. The right gain is 19, maybe 20 or 21 would be better but I don't have that option.

They are singing along, quite impressing imo. Huge difference from just the Classe. So for an upstairs in your living room setup, I am very content.

Now I have to attack the chaos of my downstairs setup lol.

 

[everettT]

Circling back here after installing the V3's with 48v power supplies. Bi amped with the Classe Dr2. Set them up and was unsure about the gain match between my c35 Classe preamp and the V3's. The right gain is 19, maybe 20 or 21 would be better but I don't have that option.

They are singing along, quite impressing imo. Huge difference from just the Classe. So for an upstairs in your living room setup, I am very content.

Now I have to attack the chaos of my downstairs setup lol.

Do you have that measurement, with the phase angle?

 

[Anglofun]

Do you have that measurement, with the phase angle?

 

[PENG]

Thanks for the input, the problem with the Kappa 9's is at around 40 hz, they drop below 1 ohm causing havoc. I tried Bryston, Plinius, Class D amps and all of them couldn't handle it. Looking at Kappa owners, they all go to monsters (like Krell or Mark Levinson)that can handle the 1 ohm demand.

I understand if you have good quality 12 inch woofers, you would not be receptive to using subwoofers, but if you are really after the best possible sound quality, you would in fact use at least one subwoofer, even a low cost one such as SVS PB2000 and HP the Kappa at 80 Hz, or even 60 Hz, then the 1 ohm dip won't be an issue. Consider the following points, before taking what those people say at face value:

1. Most music contents will simply not have much contents in the range between 20-40 Hz.
2. When the contents so frequent that range, it won't stay at constant level so there will be tons of breathing room for the amps, class AB with large PS, and class D amps should have no trouble dealing with such occasional and typically narrow dips.
3. The RS Kappa 9, based on the schematics show a switch, that if left in the off position, would add a little resistance in the crossover so you have a choice to use that switch.
4. The resistor for that switch is rated just 50 W, to me that means Infinity did not anticipate "power" requirement would not be as bad as their users might think.
5. Take a look of the short term low impedance load capability of the V3 mono:

>400 W 2 ohms mean the amp can do >200 W 1 ohm, so unless you sit far away and listen to near or higher than reference level, and listening to low bass heavy contents, there is no risk!!

Bryston amps, at least the class AB type such as the 4B series, even the primitive 4B, while not rated for below 4 ohms nominal speakers, would have no trouble whatsoever behaving well with those occasional dip to 1 ohm or below, in fact, even my Denon AVR, the light weight (36 lbs) AVR-3805 can do that. As I alluded before, people on forums tend to exaggerate their point of their speaker's drivability, it seems like to them, it is a bragging right to own speakers that need >100 lb Krell, Passlab, Bryton mono kind of amps, even if in fact, their speakers could be driven by a near flagship class AVR. Now, obviously I am exaggerating, just to make my point lol.....

Again, I understand your concern, and I love those Kappa speakers, never tried the 9, but the smaller ones.

I am not saying forum talks of how horrid to drive the Kapp 9s are, just saying it depends on individual use cases, some needs to be very concerned while some should just relax and enjoy the music. My comments are bass on facts and data, hard for any EE to argue with lol, but if just read why people post without those facts and data, then yes every users will be concerned.

By the way, between us, don't show @TLS Guy (an experienced speaker diyer) the impedance graph, if he sees it, you will tell you to get rid of those "poorly designed" speakers. And if you believe him, don't throw them out, just send them to me.

 

[Anglofun]

I understand if you have good quality 12 inch woofers, you would not be receptive to using subwoofers, but if you are really after the best possible sound quality, you would in fact use at least one subwoofer, even a low cost one such as SVS PB2000 and HP the Kappa at 80 Hz, or even 60 Hz, then the 1 ohm dip won't be an issue. Consider the following points, before taking what those people say at face value:

1. Most music contents will simply not have much contents in the range between 20-40 Hz.
2. When the contents so frequent that range, it won't stay at constant level so there will be tons of breathing room for the amps, class AB with large PS, and class D amps should have no trouble dealing with such occasional and typically narrow dips.
3. The RS Kappa 9, based on the schematics show a switch, that if left in the off position, would add a little resistance in the crossover so you have a choice to use that switch.
4. The resistor for that switch is rated just 50 W, to me that means Infinity did not anticipate "power" requirement would not be as bad as their users might think.
5. Take a look of the short term low impedance load capability of the V3 mono:

>400 W 2 ohms mean the amp can do >200 W 1 ohm, so unless you sit far away and listen to near or higher than reference level, and listening to low bass heavy contents, there is no risk!!

View attachment 76528

Bryston amps, at least the class AB type such as the 4B series, even the primitive 4B, while not rated for below 4 ohms nominal speakers, would have no trouble whatsoever behaving well with those occasional dip to 1 ohm or below, in fact, even my Denon AVR, the light weight (36 lbs) AVR-3805 can do that. As I alluded before, people on forums tend to exaggerate their point of their speaker's drivability, it seems like to them, it is a bragging right to own speakers that need >100 lb Krell, Passlab, Bryton mono kind of amps, even if in fact, their speakers could be driven by a near flagship class AVR. Now, obviously I am exaggerating, just to make my point lol.....

Again, I understand your concern, and I love those Kappa speakers, never tried the 9, but the smaller ones.

I am not saying forum talks of how horrid to drive the Kapp 9s are, just saying it depends on individual use cases, some needs to be very concerned while some should just relax and enjoy the music. My comments are bass on facts and data, hard for any EE to argue with lol, but if just read why people post without those facts and data, then yes every users will be concerned.

By the way, between us, don't show @TLS Guy (an experienced speaker diyer) the impedance graph, if he sees it, you will tell you to get rid of those "poorly designed" speakers. And if you believe him, don't throw them out, just send them to me.


View attachment 76527

Thanks Peng

You wrote:

Bryston amps, at least the class AB type such as the 4B series, even the primitive 4B, while not rated for below 4 ohms nominal speakers,

I had an 8B bridged 2 by 400 watts. It was not happy. Light up red and even clipped out.

I have (downstairs setup) 2 svs mixed one PB2000 and another PB1000 for 1st octave when listening in 2 channel so well aware of svs and subs helping out. On the INFINITY's I have a monitor audio sub doing 25hzto40hz then cut off. I wish I could loop the signal but it doesn't release the entire signal so it is tuned in by ear to just dissapear.

So far the V3's are really shining. I have played a lot of house and techno music and they can really go. So, so far very pleased!